The feeder studies (i.e., IMVT-1401-3201 and 3202) for study IMVT-1401-3203 failed to achieve their pre-defined primary efficacy outcomes. Accordingly, there was a change to the benefit-risk balance. No new safety findings were observed.

This is a 2-cohort (observational and treatment cohort) extension study for participants completing feeder studies (IMVT-1401-3201 or IMVT-1401-3202). The observational cohort will assess the durability of proptosis response of feeder studies off treatment. The treatment cohort will evaluate the efficacy of batoclimab as assessed by proptosis responder rate.

Inclusion criteria:

For all participants:

1. Have completed the Week 24 visit of the feeder study.

For participants assigned to the Open-label Treatment Cohort:

1. Do not require immediate surgical intervention and is not planning corrective surgery/irradiation or medical therapy for TED during the course of the study.
2. Did not permanently discontinue batoclimab

Additional inclusion criteria are defined in the protocol.

Exclusion criteria:

For all participants:

1. In the Investigator's judgement, the benefits of entry in the study do not outweigh the risk.